This invention relates to the area of tents and the provision of temporary shelter. Often there is a need to rapidly set up such shelters. Among standard tent designs, the time required to set them up can be substantial. A series of steps is required including laying the fabric out on the ground, inserting and attaching poles, pulling the structure erect, staking it to the ground, and attaching guy ropes for extra stability. As the size of the tent or shelter increases, the required setup time lengthens.
There are various rapidly deployable systems for tents that effectively reduce the setup time. Many of these systems are based on extensible tong linkages, sometimes referred to as scissor linkages. My own U.S. Pat. No. 5,024,031, hereby incorporated by reference as if fully disclosed herein, utilizes such scissor linkages to construct transformable truss-structures in a variety of shapes.
Such scissor linkages are highly effective in creating structures that deploy or transform. However, once the structure is deployed, they are less effective in providing an optimum structural system. The “structural depth” of a scissor linkage varies widely. In some places, there is significant distance between its links while in other places, both links overlap such that there is no depth provided beyond the individual link dimensions. This results in a basic structural inefficiency. Such inefficiency can limit the structural span, lead to increased weight, and prevent efficient packaging.
We have discovered a method that solves these problems by creating a system that is equally adapted for optimum deployment as well as structural performance. This system is based on parallel four-bar linkages.
This invention relates to means of connecting series of four-bar linkages together such that they provide a structural truss in their extended state, provide a compact package in their retracted state, and move together in a synchronized fashion.